The man turned up at the store on Spring Bank West at around 6.35am yesterday with a spade.
He left the tool outside, but once inside he began to argue with staff. The man was removed from the store and as he left he kicked the bottom glass pane of the shop window, smashing it.
Owner Harjin Derdhillon said it would cost 300 to repair, adding: "I'm out of pocket because I have to sort this out as soon as possible. They are getting drugged up and I am forking out because I am a taxpayer. It is annoying when I am doing a 13-hour shift."
The man is described as aged 35 to 45, 5ft 8in tall, of average build with short, light brown hair. He was wearing blue jeans and a dark sports top with a light stripe down each arm and across the front.
Anyone with information should contact police on 0845 60 60 222.