Unwilling to refund/exchange item after 2 days

I bought a Carriwell feeding bra from BabyCity 2 days ago. I chose a white bra but I decided to exchange it for a 'nude' colour as the white did not match any of my clothes properly. I was met with an extremely bad attitude and was told the item does not even come in that colour, this after I've seen it in that colour on their shelves before. The consultant was completely unwilling to refund or exchange the item and only after arguing with the manager I was given a voucher to the value of the item. Now I have a voucher I can't use because they don't stock what I want anymore! This is not the first time I've experienced such a bad attitude from this store before. Surely this is not in-line with the consumer protection act!?