Portcullis Surgery, in Ludlow, has apologised on Facebook for the inconvenience caused after patients were sent texts for their due date too early and they had booked in with earlier clinics with other practices.
"We have noticed a significant problem with our Covid booster clinics," said the surgery in a Facebook update.
"Patients are being sent texts by us for their due date BUT they are booking in earlier clinics with other practices by mistake."
National rules mean that people must not be able to get their jabs any earlier than exactly 180 days after their second dose.
"We have had to cancel about 50 patients who were booked too early on the clinics for October 16 and 20, we will be calling and rebooking these patients over the next few days. We apologise for the inconvenience."
Even if the appointment has been booked just one day earlier, they will have to be rebooked for a later date even if they have only come a day early for their booster, the statement continued.
"We know this is really upsetting and frustrating but these are not our rules and we have to follow them."
The statement added: "Please please if you get a text you must NOT book any earlier."
The surgery has now adjusted its text system to send them with the specific date that people can book from to minimise further errors.
A spokesperson from the Shropshire, Telford & Wrekin Covid-19 Vaccination Programme said all surgeries had been advised not to send invites to patients before they become eligible for a booster.
“The NHS Vaccination Programme is inviting eligible people, who had their second jab at least six months ago, for the booster dose. As this will be phased, people will only be able to book once they are invited.
"For people that aren’t invited to book on National Booking System straight away, or where they haven’t been contacted and booked through another service, they will be contacted and able to book in the near future. People do not need to contact the NHS to arrange their booster vaccine, as the NHS will be in touch when they become eligible for the jab.
“Shropshire, Telford and Wrekin Primary Care Networks (PCNs) have been advised not to send invites to patients before they become eligible for a booster. In line with the Joint Committee of Vaccination and Immunisation (JCVI) guidance, patients cannot be offered the booster earlier than six months (or 182 days) after the second dose of the vaccine.”
The surgery has been invited to make comment.