Bad Service and not standing to warranty

Dear Telkom i am a bit upset and do not know who to talk to. I have a contract with Telkom since 2014 and had a upgrade Februarie 2018. S8 galaxy after 2 months use phone switched off never working again also not charging. Took phone in for repairs. phone was in excellent condition shop associate also took photos and said the same no damage. Then i receive a sms from bradian Logistics saying phone out of warranty i have to pay R8000+. I queried why and what i have to pay that much for repairs.I have phoned the shop,send numerous mails i still i can not get an answer. they claim it is physical damage. how is that possible and why can they not tell me what repairs will be done and what is wrong with phone? Every month telkom deducts from my account.I feel this is poor service delivery