I'm pretty sure this (a broken unsubscribe flow) is against the CAN-SPAM act in the USA. If you can't get it working, email legal@ and complain.
To be honest, Weathertech's floor mats aren't even that good. They're okay, but I much prefer Tuxmat, which are a similar price but feel higher quality and usually have much better coverage. Lasfit is also good, if you want something a bit cheaper.
Trunk/boot mats. Those are usually pretty similar across brands - they don't differ as much as the floor mats do.