trust me I believe you, I have been on the bad end of the stick when it comes to bad service, The worst I experienced was in the UK, and Denmark. We went to a restaurant in Denmark and there was a que to get in, we got on the list, finally sat down at the table, someone eventually came to the table, my husband speaks norwegian (and they can understnd) anyway, we finally order (I appreciate it is very busy) we get our drinks (price is even higher than singapore for a beer) Like 6 pounds ($18 sing) and wait, and wait, and wait, and wait, and watch new clients come and order, and eat, and NO ONE would even make eye contact.
I got up and walked out, I tried to speak to someone, who acted like they didn't know what I was trying to say, So I thanked them for the drinks, and left!!!
In canada tipping is where the service industry make their money, in the UK, Denmark, and I find in Singapore, tipping is not customary a included service tax is added, so where is the incentive???
Some think tipping is rude, but I think it is a good practice, because if I get good service I leave a good tip. Not because you need the money but because you made me feel respected and appreciated as a customer and want to let you know.
Don't get me wrong there is bad service in Canada too and they get no money.
I would speak to the manager, and then if that is not satisfactory speak to the owner. Losing money is bad business practice and you have put me off going there

so shame on them