I ordered a set of the the second skin seat covers and had a similar experience. The website showed in stock 3-5 day delivery. I got the same recorded message and unanswered emails after days turned to weeks with no delivery. I even threatened for a refund, which in fairness to them they did say they would honour - that was one of the few emails they did answer, the others giving a revised delivery date.
I begrudgingly waited and the seat covers finally arrived two months later. I would say they are of exceptional quality and reasonably good value for money. The customer service, however, is exceptionally poor quality.
I know it will leave a bad taste but I would wait it out because the next comparable set of seat covers are about £150 more. In addition the Inka covers also come with two cushions.