Horrible Upgrade

I had a scheduled upgrade for August 2021, I phoned in and chose the device, Samsung A72 as advertised on their site, we arranged everything and they promptly told me it will be delivered within 7 working days. 2 months later and I still received no device, after numerous attempts at sorting it out, I am told that the device in question is no longer available on their systems, (note it is still being advertised) February 2022 I phone and select a new device the Samsung S21 Fe, again through the whole process, all is settled and it will be delivered in 7 days, now I receive a sms stating that this device is also delayed and I may not receive it. I phone, only to be put on hold via the transferring of the call to another department, I wait on hold for 15minutes with no answer I decide to send an email enquiring to *** still no response 4 days later, so I phone again only to be put on hold again for 10 minutes. What am I supposed to do to receive my new device for which I have been loyally paying since the start of my original contract ?