Hi, I had same problem. Tried to bet $CAD20 on 4 different games @ simple odds of around $2.00. Said "stake too high... will adjust accordingly". It lowered my stakes, I tried to execute bet ... same thing ... still "too high". Not being able to bet CAD$20 on a simple single at odds around the 1/1 or $2.00 mark is ridiculous in the first place. The auto lowering and rejecting and lowering again of my stakes .... just a joke. Tried online chat help - totally useless. I am closing my UniBet account - a few hours after I opened it.
Find another bookmaker. These don't deserve my business.