Heat Tech Geysers Warranty Service

I am struggling to get Heat Tech to attend to a burst geyser since Monday 15/2/2021. Today is the 19th. I sent numerous emails reporting the burst geyser. I called the office-hour number and spoke to a lady and gave her all the info about the geyser. Nobody contacted the client. I phoned the after-hours number and a lady answered and told me to send a WhatsApp. I sent five WhatsApp messages and received no reply although I could see the person is online. I phoned the number again and no-one answered. My client is a restaurant in Durbanville. They are being without hot water now for a week and I just don't receive any service from Heat Tech. The geyser is under warranty and it is burst. I will most definitely never install a Heat Tech geyser ever again since this lack of after-sales service is absolutely unacceptable. I am terribly disappointed.