We Fix makes their repair error my problem and my cost

i took my i pad in to we fix melrose arch on 20 Oct 2018 to replace the battery i was told that a battery was put in by the technician the next day, but it was not working so a new one needed to be ordered, told that it would arrive on Monday 29 October and technician would have it ready on 30 Oct. after no contact i enquired and was told the technician would only be doing it on wed 31 Oct. that date came and went with no contact. in frustration I contacted again on 1 Nov and was told it was still being worked on . Manager nomsa not available. i left a message for her to call me. Friday 2 Nov no contact from manager, but was called to say the i pad was ready and messaged as well. short while later i was called again to say that the touchpad was ghost typing and would have to be replaced at my cost. there was no such problem when I brought it in so I objected. the best I was offered was a 5% discount. i collected it on Saturday 3 Nov and once again I strongly objected to paying for a repair that needed to be done that was not faulty when i brought it in. The technician told me that I should have been told that things can go wrong when repairs take place as the item is sensitive, He showed me my old touchpad and said that it was still perfect, but during opening and closing things can go wrong and cause a problem. I was never told, warned about this. the regional Manager Ike was contacted about my complaint and he told the staff member on duty to give me a 10% discount. i had no option but to pay the amount as i needed my i pad. the situation is very concerning and not fair business practice in my opinion. I believe i should not have been charged for a repair that was necessary due to something that went wrong during the work done on my i pad. I feel unfairly charged