Non-stop spam for 2 months

For the past two months (maybe more), I keep getting SMSes and robo-calls from Buffalo. According to them, I am Diedrik Fourie, with order number BUFZA***YQ, and I haven't been available to collect my parcel.

I have spoken to warehouse dispatcher and I have spoken to drivers, telling them I am not Diedrik Fourie and I didn't order anything. I have told them whoever entered the phone number, must have done so wrongly. I have called South African numbers on their site and been on hold, only for the call to get drop MULTIPLE times when I'm next in the queue to speak to an operator. I have emailed them.

All to no avail, as I keep getting spammed via SMS and robo-calls. I really would like to for this to stop. I don't know why they don't just contact the sender of the parcel, Bash, to find out details of this person (such as email) and contact them via that method.

STOP SPAMMING ME, BUFFALO!