Free trail????

I received an offer from Netflix for a free trial. I thought it was great as I am in a rural area and wasn't sure if it would work here. When signing on, I realised they wanted financial details from me. I had a live chat with Eric and was told I would not be charged and that it was for my benefit so that I don't miss out on anything. On further questioning he said they would contact my bank and though they would not take any money, it may affect my balance?????? I responded by saying if I liked the product and it worked well here, I would of course subscribe quickly. A free trial should be free with no strings attached, not so? Netflix, I enjoyed your service while I was in the UK but this free trial seems to be not completely free after all