Poor signal strength

I upgraded my cellular phones and was required to do a Sim swop as the new phones take different size Sim cards. Ever since I have done the Sim swop the reception/signal strength is extremely poor. I can barely hear the person on the other end but they can hear me clearly. I have never been so frustrated before as I use one of these phones for business. Doing the Sim swop was the worse decision. It is clearly not a phone issue because placing the new sim card in my old phone still gives me poor signal strength and poor voice quality. I did not have this issue with my old sim card. I am extremely disappointed as I did not expect to run into such an issue. I logged a service request call with 111. The reference is s3-8543p-p63ci. I am still waiting to he contacted.