Average food. Upset about tip - what gives your es...

Average food. Upset about tip - what gives your establishment the right to automatically add an 18% tip for a party of 4. Didn't notice that on first of 3 pages of receipts. We then added another tip. Service was not deserving of this tip - had to ask for refills, didn't tell us what the cola product actually was and he twice tried to get us out of there by making comments about turning the table over. Not impressed.