If you’re going to offer customer support, and in most cases you should, then do it properly.
Don’t make it difficult for people to get support, don’t make people have to continually chase to get a response, and don’t offer something if you can’t provide it.
Most importantly, if customers are paying you for a product or service, don’t expect them to wait around patiently while you sort something out on your end. You’ll very quickly piss them off and turn them from a paying customer to a disgruntled customer that is happy to talk about their experience online or through reviews.
Customer support should be easy, for both you and your customers. Put the systems in place to make it this way.