Indeed they DID do the song called IOU, but it is the same song that has the chorus that goes 'A, E, A, E, I, O, U, U, I sometimes cry' (although, back when it was released, most people seemed to think that it was 'and sometimes Y')
A E I O U (and sometimes Y) was an original recording by EBN-OZN an American duo in 1983 on the Electra label. Robert Rozen and Ned Liben, the duo, split up shortly after, and EBN-OZN are known as one-hit-wonders. Freeez, a British funk group, recorded I O U also in 1983 on the Begars Banquet label. This record has no connection with EBN-OZN's. The lyrics are totally different. The first 2 lines of I O U are A E A E I O U U, I sometimes cry (repeat) and the last line is A E A E I O U U, I sometimes lie. So, Allday, I guess that if you heard this catchy tune in the UK what you are thinking of is I O U by Freeez.