At around 9.10pm on Wednesday 15 July, a man in his 40s was outside Aldi on Woodchurch Road when he was approached by three men, one of whom was carrying a baseball bat.
Two of these men are believed to have attacked the victim before making off on foot.
The victim was taken to hospital with fractured ribs, and bruises to his body and head.
CCTV and witness enquiries have been ongoing.
Detective Inspector Laura Lamping said: “This was an appalling attack on a man, resulting in serious injuries and understandable distress, and which appears to be a dispute about the non-payment of a taxi fare earlier on.
“For such serious violence to be used in these circumstances is despicable, and we’re keen to hear from anyone who was in the area and saw the incident, or any argument which preceded it.
“We believe the man pictured may have information to assist, so if you know him get in touch.
“We’ll act on all information to find those involved, so if you have CCTV, dashcam or just know something, come forward and let us do the rest.”
Anyone with information can contact @MerPolCC or call 101 with reference 20000429375.
You can also contact the independent charity Crimestoppers anonymously, on 0800 555 111 or via their online form at: https://crimestoppers-uk.org/give-information/give-information.