Faulty geyser

Hi, on 1May 2020 a Duratherm Geyser was installed @ my house, luckily on the outside wall. On 12 May @around 10h30, hot water was pouring out of the 1 outlet on the geyser. The power supply to the geyser was switched off, and later we closed the main water supply in order for the overflow to stop. I reported this to the plumbers who did the installation. They informed me that the geyser's warranty do not allow them to do anything to the geyser after installation. I phoned Absa, our insurer. They lodged a complaint with Fogi. Since then it happened twice. On 15 May, plumbers came and changed the thermostat which was appemarently bent. That afternoon @18hr the hot water was pouring out again. On Monday morning I phoned the bank again. The lady phoned Fogi who was supposed to phone me in 2hrs time. I'm still waiting for that call. Monday night the water was pouring out again.We do switch the geyser on from time to time. We need to take a bath and wash dishes. Since Mondaybwe kept the geyser off. I phoned the bank again on Tuesday, the agent gave me the email of Sihle Madlala who works on our case. I mailed him that same day, till tiday no reply from him. On Wednesday I send an email to hoc claims @ absa. They rep**** with a case nr. Since then, no other response. Yesterday I spoke to a lady @ Absa again and she asked me to send a mail to Duratherm, the numbers listed does not work. I would really like this to be resolved. I know we are in lockdown, but geysers are essential.