bad service for a paying customer

I took a Samsung A3 from MTN The phone overheated no apps could open I could not even use the phne I thn decided to tke the phne bck firstly the MTN store upstairs in sanlam center was closed in the afternoon at pass two on Friday 17 July I w8d for them to open for 40 mins eventually they opened . I said I'm returning the phone bcz its giving me problems they checked and then said they will book it . I left the store they called me bck after 15mins to say there is physical damage on the phne reason being when I took out the phone they were in such a hurry to close the store bcz it was almost home time they did not show me how to insert & remove the sim and memory card resulting in it bending slightly which is nt even the initial prblm the problem is the battery . they told me when i went to the other mtn store that i have to take the phne bck 2 the store i took it out from yet in the contract it stipulates i can take it to any mtn store and no where in the contract does it say because of physical damage resulting in their negligence they cannot repair or return the phne. 4a good paying client this is disgusting they r lazy they told me to take it to samsung in canal walk