Hi Sense TV's

We bought 3 Hi Sense Smart Televisions from Hirsch Centurion. Once installed, we realised that our TV's are constantly buffering. After making some enquiries etc we decided to upgrade our Wi Fi from 10mb to 20mb, which, according to the experts, should be sufficient in our household. Still we were having constant buffering while watching TV. We went back to Hirsch who then suggested we upgrade again - which we did, to 50mb. But we still had constant buffering. Hirsch then booked a technician from Hi sense. This took a while! In the meantime, being really desparate, we bought a Samsung for the lounge as we were sick and tired of watching a 30 min programme, that takes an hour! We had NO BUFFERING! The tecnhician came out, rreset, etc the 2 remaining televisions. Still we had buffering! We booked another call. The technicians came out and adjusted something.... Still buffering. And again, and again. Then they decided to replace the "mother boards" i believe - still we had endless buffering! We had enough and I tried making contact with some more senior people at the Cape Town offices, namely Robin or Nathan. I was totally blocked from speaking to Robin. I did manage to explain to Nathan what the situation is. 3 days later I got a call from the technician, saying he is collecting the TV's for testing. No word or even a message from Nathan! The next workday, I get an sms that the job has been completed (which is a standard sms and I have had those many times). Since monday, I have been trying to call Nathan, left messages for him or Robin. I made 19 phonecalls in these 3 days, got thru twice and I still have not been able to speak to any of them. We dont know where we stand. They cannot even keep us informed of whatever the process is. HI SENSE SUCKS!