Fresh Force in Frankfurt am Main

I wanted to try Bibi's Burgers with two friends for its three-year anniversary. The owner advertised that they were offering free burgers from 3 p.m. to 6 p.m.... We arrived at 5 p.m. and were immediately told that there were no free burgers! This makes me wonder why they explicitly advertise that the anniversary promotion is valid from 3 p.m. to 6 p.m.? To me, this is a lousy trick by the owner to lure customers into the restaurant and then charge full price, which I realized later. Since we'd been there before, we ordered a single burger to try. We didn't receive it for an incredible 70 minutes. We asked several times, but were always told that our burgers would be ready soon. We also saw others cancel their orders or simply leave after an eternity... just as we were about to cancel our order, the burgers arrived. I have to say, the burgers are good and delicious! But waiting 70 minutes for this is unacceptable. If we hadn't had something interesting to talk about, we would have left sooner. In any case, we won't be coming back and can't recommend Bibi's Burger!