~snip~
As the support agent has said it to you, the betting limits really depend on the odds provider. Although the betting site sets a max bet limit, but the odds provider reduces the max bet limit for some users by following their betting patterns. The live support agent has nothing to do there. Your max bet limit may decrease more if your betting patterns remain same. Do you always place bets on those events where the risk is too low? You can read this article to get some information about your situation:
Dealing with Account Limits at Sports Betting SitesI don't see anywhere in your article it was something decided and applied by odds providers. Where have you seen that? The customer of the casino, is not the customer of the odds provider, there is no reason for them to make things like that on their own. It's not their business. I think it's just a BS excuse from the customer support, to avoid complaints from players and getting a bad reputation.