Strong lenses

I purchased Glasses at spec saver in Atterbury this year early t(I have to check my bank statement for exact date), I did the eye test and choose the frame. The glasses came back and they called me for collection and I went there to collect and asked me to put on the glasses yooo they were so strong and I couldn't see things properly and they said I must wear them for few days and I can bring them back if am not happy okay fine I did that and I they were still strong I called them and explain my situation to them again and they said I must bring them back, I took them back and we did the eye test again the Dr said she will reduce my lense, after few day they called me to collect and I asked them to courier for me. The glasses wer better that before but now I can feel that am suffering. You can feel the strong-ness when you put them on and off. I think my eyes are being damaged now. I've been using Optometrist for the past few years but I never experienced this. I really miss my Optometrist unfortunately he moved to MP. I think It was my first time and last time using Specsaver. What must I do with the glasses now? Please Help