Phone Trade-In Ripoff

Displeased with Samsung for not walking the talk.First , I took up their offer on newly launched S21 5G and bought it from their online store & paid cash via eft. Took time for delivery and when I voiced my concern, only then was it brought to my attention that the colour I initially required was not in stock and agreed with them to send what was in stock and got it promptly with promo items(buds and tag).Days , after they send me an sms on a R3000 promo trade - in of my old phone and included a link to use to take up this offer.I duly entered my details of the old phone and new phone, but their provided link failed to authenticate the phone IMEI, and i phoned them several time to bring this to their attention and was promised call back by senior manager, a promise never kept.Send countless emails to no avail.Last call made, I got a reference *** and was assured this reference would be logged on their system and should expect a callback and still this was never kept and in the meantime, cutoff date on thisd tradein offer came and went, and only then did they both to respond via email that cutoff date has past which surely was a tactic utilized to their advantage that is not in line with best customer service from such a "reputable company". Worst part is , it was not my initiative to do a trade -in , but theirs to look good in the eyes of consumer???How can IMEI be invalid if both invoices and search on phone settings as well as using USSD corroborate each other????