Luxurious Afternoon Tea in London for Two

To celebrate our Ruby Wedding, our daughters bought us a tea in the Georgian Restaurant through Red Letter Days and everyone thought that covered the full cost. It proved impossible to book a date through the Red Letter Days webside as instructied and there is no phone number. Eventually live chat told me to phone Harrods direct and then it was easy but the voucher doesn't show the number. We presented the voucher on arrival as required and nobody mentioned there being more to pay. Whilst service was a little on the slow side, it was an enjoyable tea served by polite staff. The pianist added to a lovely atmosphere but it was a shame quite a few other people did not really dress for the environment. What rather spoiled our gift experience was the waiter arriving with a bill at the end and whilst we pointed out we had used a voucher, he said we still had to pay a service charge. The bill was for £19.50 and as we didn’t want to make a fuss spoiling our day, I just paid it when he brought the credit card machine. The other thing that seemed unusually poor was the distance from The Georgian to the nearest toilets. Signage was not helpful and having to get through some crowded departments, I really think it must have been a five-minute walk each way. I would not object to a polite note saying that the gift experience did not include a service charge as a subtle hint to leave something for the staff but presenting a bill does not seem the best way.