Aaron Fee, from Sunny Mede, said he dropped his phone at the charity’s base on Queen Street on the afternoon of 23rd November.
He returned later that day to pick it up and began arguing with staff.
Catherine Picardo, prosecuting, said: “He was verbally abusive and was under influence of drink.”
Fee apologised for cracking the glass. He was fined £65 and ordered to pay £50 compensation.