what's your proprietary advantage? you say their site is better. maybe start there?
this is a very old problem. most companies in the early 2ks bought all 3 domains, but when they started offering dozens of tlds, it was difficult. then your only two options were trademark or being the best.
if you don't have a trademark, you have no chance of protecting your name.
i think you can fight it in court if you have the money and time, but you'd have to convince the judge that your brand has value. a whitelabel is your name on someone else's content. i don't think you have any IP to protect.
your only option is to be better than them.
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