Electronics repair shop holding my amplifier

[Maplicito]

I'm wondering if anyone has an opinion on this one, and has an idea of what my rights would be.

I had an amplifier of mine taken to an electronics repair shop. The agreed upon service was $25 for an estimate. 3 weeks later, we were contacted, and told that the amp was repaired, and the charge would be $200. They were immediately told that no repair had been authorized.

I tried to negotiate with them, and offered to pay $100 for the amp, or they could pay me $50 to keep it. I was told that no, they would rather undo the repair, and charge me the $25. I went in a week later to collect the amp - they have done nothing with it, and I was told it will be at least another 2 weeks as they are going to put their time into projects they are "being paid for" instead of mine.

I have a few problems with this. First of all, they only thing they are losing is labour - they put no parts into the amplifier, so there is nothing for them to reclaim from it. Second, they made it clear that they do not guarantee that their "unrepairing" it will leave it as I brought it in. I do not want them touching it and risking further damage, and I feel they have not dealt in good faith, I feel I should have no obligation to pay for a service that was not asked for either.

Do I have a right to demand the amplifier back, in its current state, for the initially agreed upon $25? I asked the police this same question, but I was told that because the area of law in question is not criminal, they can't really help me.

Thank you for any opinions.