Contract arbitration between London and its firefighters is getting hotter, after a panel ruled a consultant — hired by the city to help prove it can’t afford to pay firefighters what they want — isn’t an expert on the issue.

It’s unclear how much the city paid Michael Dobner from accounting firm PricewaterhouseCoopers, since calls for the information weren’t returned.

Mayor Joe Fontana said he didn’t have the number at his fingertips, but found the arbitration panel’s decision “baffling.”

“We heard what the arbitration board has said and we’re a little perplexed by it because the witness we brought forward from a reputable auditing firm has great knowledge of these issues,” he said.

The city isn’t giving up, however. Fontana said the city will “enhance” its points with additional expert witnesses.