Short version, keep calling them on the phone until you get someone and keep following up one the phone until you get the issue resolved. Don't email.
We were doing it during the middle of the heat of covid, but we had an issue with one of the sway bar blocks on our BOSS coilovers. I called them, they were very agreeable about sending a replacement out. Then a week went by, and another. It took about a month, but only because I was too lax on following up (that shouldn't really be true as a customer but you know...).