Poor service by Experimax Paarl

I took my Apple IMac to Experimax Paarl Branch due to Hard disk problems. They charged me a R1500 to put the Hard disk in the IMac because they need very strong glue to fix the screen according to them. I paid them the R1500 and I bought two External harddrives from them plus a secondhand Apple Iphone from them. Spend in total about R13000 at their store. A couple of weeks after put the hard disk in and fixed the screen, the screen of the IMac simply fell off. Experimax Paarl refused to come and fix their bad work on my premises stating that it is not policy. I took the IMac in to their store after they promised me it would take about 2 hours. I took it in on 21 August 2020 at 9am and at 4pm I had to phone them to find out out if they are done. The technician told me they are busy running tests to make sure it does not happen again ( not sure which tests can be run to avoid the screen from falling out ). Then i drove to the shop myself and when i got there, the IMac was still on their counter in two parts as i have handed it in, and they did nothing. It is unacceptable that they are lying like this. I took the IMac away as i do not trust this business at all anymore, and will now have to pay another Apple Approved shop to fixed their mess. I demand a full refund of the R1500 i paid them. This does not even take into account the time and inconvenience it caused me.