BAD Service & Breech of Contract

I'm disgusted by the fact that Speed Trainer Somerset West has sold my lay-by whilst I was still making payments well within the time-frame. Yesterday, 26 February 2019, I went to redeem my lay-by, only to find that they couldn't locate my shoe, and that it had been sold. I've spent 3months paying this off, only to leave empty handed. I am disgusted in the negligence you've portrayed and now I cannot find the size I require anywhere.