Samsung S6 - Glass Repair.. Main Board Warranty

I bought a Samsung S6 through vodacom.. My phone fell and had the Glass Repaired.. in this they noted that the Main board was damaged and they must replace it.. after a month they confirmed that it was manufacturer defect and they will replace it.. after having it received nearly a month and half since taking it in.. i received my phone back.. since getting it back i have complaint after complaint that my phone sounds like i am underwater. Took it back and they were adiment that it was Network.. i then noted to my provider that there is a problem with network.. they never responded.. however i took it upon myself to place my sim card into another phone (same make s6 edge). Called number of people no complaint.. this comfirms that Samsung has messed up my 13000 phone.. and when i take it back to the walk in centre they are adamant that it is network. The speaker phone over and above this does not work since repair.. i am tired of driving up and down with this.. i expect more from Samsung. I am starting to loose faith in Samsung all together with this.. come on guys!! Let me gues take it in for repair and sit without a phone for another 2 months and expect it back broken..