Stemz Global - Rescheduling of Covid test

Hello,
Health Passport Number: *****
I required a covid test to board a flight on **/**/****. Owning to unforeseen circumstances, the carrier had to cancel the flight on **/**/****. Stemz global had previously acknowledged that I would be able to reschedule my appointment scheduled on **/Jan/****. With this in mind, I requested them for cancellation for the day. Hence no sample collection was done for the test on that day. Once my flight was rebooked, I contacted them again to reschedule the test. They have refused to proceed with it asking me to read their terms and conditions. Their terms made no mention of rescheduling, only a cancellation policy. Most importantly, the sample collection was not done on the day of the test either, so I am not in receipt of their product owing to this misunderstanding.