Idroid lab and mtn are disappointing

My phone had liquid damage mid August,i called Mtn and the send a courier to collect my phone after 3 weeks it was sent back but the phone was shutting itself down after few minutes of opening i called Mtn again and they sent my phone back to Idroid lab and when they send it back after two weeks it had the same problem i called them mtn again and i even called Idroid lab to explain the problem and the phone was collected again and came back on the 22 of November and it still has the same pro lem after almost 4months of them trying again and again but still the technicians were unable to repair the phone. I dont know if the check the phones before sending them back or something. Idroid im very dissapointed, im waiting for them to collect it again.