Disappointing customer service

Have to say right off the bat that I am incredibly disappointed with the customer service at this place. I had made a booking for 4 for Christmas lunch and unexpectedly received an additional guest who is staying with us for Christmas. I sent an email query through, asking if I would be able to add on 1 more guest as I cannot now exclude them from Christmas lunch whilst they are staying with us over the holidays. I received no response to my email for 2 days, despite having sent it to 2 different email addresses. I then sent a whattsap message with my query and a further email to 2 other email addresses, after which I received a response nearly 5 hours later (via whattsap), with no apology or explanation for why my emails were not attended to. The response was "Unfortunately we are fully booked." I then sent a whattsap message asking if I can rather be refunded to which I again received no response. I then called in to 2 different numbers (the first of which was not answered) and on the second number, spoke to someone who did not provide their name and was told that I must "drop an email" to Samantha who I assume is the manager and that she is the only person who can assist but is currently on leave. So in her absence everything just stands still? There is no one available to assist customers with any unforeseen issues that arise? Needless to say I informed the person on the other end of the line that "Samantha" was not responding to my emails, and the response she gave to me was "she's on leave." Quite ridiculous. And further to this I was also told that if I want to cancel, then I will not receive the R869 deposit which I paid! In what world is it okay to charge someone R869 for food that they will not be eating??? I also did not see any mention of this in the terms and conditions when I made the booking. I am disgusted and completely put off by the way these people treat customers. I would not recommend booking anything with them unless you are 100 percent certain that something unforeseen will occur (as if that is even possible!) Rather book at a place that has a better reputation of how they treat their customers, not at a place such as this that only replies to emails and messages when they want your money. Extremely dissapointing service indeed.