Soapy milkshake

Avoiding the iftaar rush I went to spur later to get food that I pay for and was glad that I did,well done. The problem that I would like to bring to your attention is the lime milkshake which taste as if they put sunlight liquid and not the actual lime flavor itself. I ordered a lime milkshake to which it tasted like soap,called the waiter and he gladly exchanged it,the manager arrives and informs me they are not sure how it taste that way and if they should add more or less syrup and it could be the reason it taste like soap. Weren't you guys suppose to test the recipe before offering it to customers??Honestly speaking I can't fathom how that's possible. When the new milkshake arrived It tasted exactly the same as the first,took one sip and left it. Is the soapy flavor the new lime flavor for spur?