Rank up bug with coin exploit issue

My son plays PvZ GW2 his electric pea that is a specialist went up to level 11. Every time he goes to rank up the electric pea to go to advanced it goes to level 2 and he gets the 20,000 coins. Here is the second part of the bug, when he goes to multi player his electric pea goes back to level 11 specialist and he still has the coins from the last rank up. He can keep doing this and rack up coins. He tried turning the game and the console off, restarting and reconnecting but the bug persists. He does not want to get an account ban for exploiting a bug so he asked me to post it and he has turned off the game.

John