MTN and SAMSUNG

I upgraded to a new Galaxie S9+ about 3 weeks ago. With in the 1st werk the phone gave me trouble with dropping calls. Took it back within the 7 days and they gave me a new phone as MTN said there are problems on the S9 silver with dropping calls. They didn't have the black one so they gave me another silver and said I must see if it does the same. So the new phone was also dropping calls and took it back again within the 7 days. Another guy at MTN said no it's only the settings and changed the settings and said I should go try it again. In that same week still the same cutting of calls. Went back today to go and get another brand device and now they don't want to help me as it's not with in 7 days. The guy that changed the settings that said I should go try it again was there and didn't say a word to confirm I was there. I use the phone for business and don't have another phone to use as they need to send it in and will take a week. Also phoned Samsung but they just directing me back to MTN. Not to wait a week they said I should go during the week to samsung in Midland to get it sorted out. Very disappointed in MTN and in Samsung as this is not the 1st time I'm having trouble with a Samsung. My Tab bombed out in the 1st 2months. Sent it in for repairs and not soon after bombed out again.