Insect in sealed tonic water bottle

I bought a tonic water at the Checkers in Parow centre Cape Town, the brand was Eastern Highlands. When I got home, i found a small insect in the sealed bottle resembling a mosquito. I called the branch and got told by the manager i must come in and they will refund / exchange it. I mean WHAT!? I must drive 30kms for something i didn't cause? what if i drank it? what if it was poisonous? what if other bottles contain the same insects? Checkers and Shoprite what does your QMS say about these kind of cases? Do you have one in place. Im deeply disturbed by this matter.