Horrible attitude, unhelpful call centre agents

I have a contract mobile phone, and purchased R69 worth of data at Woolworths to top up. Unfortunately I was not told by the sales agent that I would not be able to top up my data by purchasing in store because I did not have a top up contract. The rude people at the call centre told me that there was nothing they could/would do. Well, the supervisor at the call centre did say that I could sell the voucher and that that was the only solution to my problem. I just want to able to use the data that I bought, and not to waste my money!