LONDON, ONT. -- A limited supply of vaccines is causing the Middlesex-London Health Unit (MLHU) to delay when they will start taking rebookings for second doses of the COVID-19 vaccine for those 80 and older.

As of Monday the province has opened up accelerated second doses for those 80 plus, however the MLHU says they are not yet in a position to do so.

"The province indicated those 80 years of age and older could begin rescheduling their second dose appointments as early as (Monday) morning, given that some health units have more vaccine supply than needed for those seeking first doses in their areas. That is not the case in Middlesex and London, when most vaccine appointments continue to be first doses," read a statement releases from the health unit.

The health unit also confirmed Monday they will begin taking rebookings on June 7, a week after much of the rest of the province.

Many residents already have an appointment for a second dose, the accelerated process is in place to allow some to possibly get their second shot sooner than the original four-month plan.

Several viewers reported that they were unable to get through to the health unit Monday morning, believing they could begin rebooking.

Marlene Lasenby, the main caregiver for her husband Fred who is undergoing cancer treatments, was frustrated by the phone delays and confusion.

“It was terrible, it was ridiculous,” she says. “The line was busy constantly and then the line was out of order, it was frustrating.”

Fred has both of his shots, but 80-year-old Marlene is scheduled to get her second shot in July and wants it moved up. She’s going to try again next week.

“I just want to get our needles and move on like everybody else does.”

It was on Friday the province announced plans to make appointments for accelerated doses available Monday morning.

In response to the move the health unit said they were working on a plan to accommodate the change in direction.

In recent weeks officials with the MLHU said they have plenty of capacity but have been working with limited vaccine supply.

In a virtual media briefing Monday afternoon MLHU Medical Officer of Health Dr. Chris Mackie said he shares in the frustration.

“The decision to rebook seniors, although it was made at the provincial level, is not actually functionally possible in many places...The problem seems to be that there is more vaccine than needed in the GTA community for first doses, I just don’t know why the solution isn't redistributing those vaccines to those who need it most.”

To see who is currently on the health unit’s list follow this link.

On May 19 it was reported that the MLHU would not receive additional supply after a pitch was made to the province, meaning the local supply remains limited.

- With files from CTV News London's Nick Paparella