、。。
In that case, I want you to grant me a wish. That'll make us even.
Literal
If-that's-the-case, I [gen-の] request [obj-を] listen [want-欲しい] [nominalizer-の]. With-that, even.
だったら 'in that case / if so' is the casual conditional. お願いを聞く (literally '(to) listen to a request') is the stock phrase for 'to grant a request.' ~て欲しい is the desiderative for wanting someone else to do something ('want [you] to X'), distinct from ~たい 'want to X (myself).' チャラ is casual/slang for 'even / squared up / zero balance,' used for mutual debts or favors.