The Dysfunckshonalz!, Bush Theatre, London

Couples looking back on the past often differ on the details of their shared memories ("We met at nine!" "We met at eight"). When the reunited punk rockers John Smith and Marc Faeces do so, the mind plays its usual tricks. "Oldham nick," murmurs the laid-back, indeed supine, John, "Oldham. That was the last time we shared a cell." The more irritable Marc corrects him. "Harlow was the last cell we shared. Oldham was the second-last."

The comedy of codgers just a few years from a bus pass quarrelling over arrest records and loading stiff, wheezing bodies with skulls and chains is well exploited by Mike Packer in his third play for the Bush. Thirty years after their glory days as The Dysfunckshonalz, Marc and John have got together with old colleagues Louise Gash and Billy Abortion. The last, now part of the quieter world of shelf-stacking, has needed much persuasion (and some oral sex) to don the motley, for the motive behind their reunion violates his principles. An American company has enlisted the group to perform their old satirical song "Plastic People" to promote – of course – a credit card. Instead of ridiculing consumers who equate shopping with living, they will now urge them, "Fulfil your destiny with a Freedom Card!" At least, that's the idea.

Billy, embodied by the inexhaustibly violent Rupert Procter, rages so wildly about the money-buys-everything attitude of our society ("Apparently the world's changed, so the truth has changed!") that it is hard to believe his (off-stage) decision to sell himself. Not surprisingly, he soon reverts to his penchant for spectacular self-destruction. That lack of surprise is the core problem of Packer's play, one not surmounted by Tamara Harvey's spirited production. There is only so much a director can do to disguise a mechanical up-down, success-failure, disaster-rebirth narrative that is a poor substitute for growth, development, conflict, and change.

Nor does Packer supply enough dazzling one-liners to override the stunted plot. While Billy's insults are amusing, too many seem like ones he's made earlier, and this, together with his lengthy, repetitious rants, makes him sound more like pub bore than glorious rebel. Indeed, Billy's one-note personality points to the more fundamental problem of the play – that the four rockers have barely as many character traits among them. If action is to proceed, as it should, from character, it is not, with this lot, going to put even one foot in front of the other. Most static of all is the role of the representative of the credit-card company: the lovely Josephine Butler is forced into a hopeless struggle with a part that is no more than a lot of sticky-taped bits from second-rate sitcoms.

Packer adds a few "serious" touches – death, cancer – but these are too slight and sentimental to give any texture to a play that treats both characters and subject with so little conviction. Much that could have been explored – the English love of failure, the old-hating young turning into the youth-hating old – is barely touched upon, and the audience's enchantment with Billy and his crew is taken for granted. Is the American company's desire to make money from greed and self-delusion so much worse than the punk band's career of glamorising wild sex, self-righteousness, nastiness, and shock?

As the most raggedy man in this ragged band (he looks as if he has slept in a moth-infested hen house), Pearce Quigley's John provides a restful as well as a reliable source of comedy as the drummer who has lost his sense of rhythm, in speech as well as song. This dreamy-eyed fellow in a Jesus beard gives a welcome lightness to a play that is full of self-righteousness but nearly free of conviction.

To 22 December www.bushtheatre.co.uk (020-7610 4224)