Can a doctor's office withhold my medical records because of a stupid paper I signed?

I was 18 at the time.Just finished my appointment and was going to pay my copay. I was told that I had a balance from when I was 16 that my mother never paid. I was told I had to pay my balance b4 I could get my prescription, b4 I could make a follow up appointment and they would not let me leave until I paid or signed a piece of paper stating I owed them money. I was there for a reason. I was embarrassed to be there for that reason and did not want to have to be even more embarrassed at another doctor's office. I had gone back to the follow up ONLY because my insurance paid for it and I had no form of income at the time. Now it's 4 years later. I have attempted to have my records sent to 2 different offices in the past 4 years. Both times I tried I was called and told that they would not be sending my records until I paid off my balance in full and that I had asked for this when I signed that paper. They will not give me a copy of what I signed. Can they withhold my records?