Terrible Service and Assistance

My father, based in the USA, passed away last year and left me an inheritance cheque. Immediately on receiving the cheque, I opened a new account with FNB because I was told they were the best with handling forex, and handed the cheque in to be cashed (8 December 2021).

At the time I was told it'll take 2 weeks to clear, which turned into 6 weeks because it was a substantial amount, and now 10 weeks+ with no end in sight.

It has been 2,5 months now with absolutely no progress from FNB, the only response I get is that they're waiting for the American bank to get back to them and that I must phone the US company to expedite the process.

Surely FNB should be helping with that? Is that not the exact reason we have to give our cheques to the banks to handle? They have made absolutely no attempt to expedite the clearance, and absolutely no attempt to communicate with the American bank or me for that matter. I have to be the one constantly contacting FNB and asking if there is any news. To which I have just been brushed aside as a nuisance.

Will I get paid any interest incurred on the money from this 2,5 month clearance delay? I doubt it, so who is pocketing that money? I expected better from FNB and as a result of this saga I would never recommend them to anyone.