My experience has been quite excellent with the after sales support. I sent a mail to firstname.lastname@example.org and got a response really quickly from a lady by the name of Charlene. The collection process then followed (took two days) and the assessment took another day and repair happened shortly after that once I had given approval of the repair (R600 odd which i thought was decent).
The return process then took a couple days which I thought was fair. I'm based in Gauteng though and if im not mistaken, Zest is run from Cape Town so the process might be a lot quicker for you! But as I said, give email@example.com a shout, they respond super quickly!