Bad customer service

It is really pathetic that I have to call constantly to Supersonic to ask them to send me my voucher so that I can I can redeem my voucher. I have been trying to sort this out since 23rd March 2020,it is now the 25th March 2020 still nothing and when I called them they ignored my calls and just told me I have to wait till the 26th to be sorted out. Really now entire 4 days to sort out this and then I am the one spending money to call them. They even placed me on hold when I asked to speak to the manager and blatantly ignored me. How is that for customer service and I have the screenshots to prove how they just ignored me