Rubbish service, items priced incorrect

We visited the drake house store in Sheffield at the weekend, we found the store layout good and found everything we needed easily. We spent over £200, which I had to discover myself by
Leaning over the till as the check out guy seemed reluctant to disclose the cost of our purchases! I thought it seemed a little bit expensive for what we had so checked my till receipt to find we had been charged an extra £10 for one item. We were told to go to the, and I use the term lightly!, customer service desk. A young girl looked over the receipt and consulted, whom I believe was the superisor? Not really sure as he didn't introduce himself to us, he then proceeded to tell us that this item had been priced wrong and we would have to pay the full price, we did argue the fact that it was their fault it was priced incorrect not ours, we were then joined by security and another member of the team and was made to feel that we had priced it incorrect by swapping the labels! we felt totally degraded and was made to feel like criminals for their lack of competence. The customer service in this store is diabolical and we shall not be using this company again. I know it was only £10 but it was the way they spoke to us that was insulting, surely for what we had purchased they could have honoured it as a good will?. We don't hAve a store locally to where we live and have to travel to any major toy outlet so next time we shall be using good old toys r us.