HALIFAX -- On the same day Nova Scotia expanded eligibility to reschedule second COVID-19 shots, some residents are expressing frustration about being unable to move theirs up.

The online booking system automatically scheduled second doses 105 days later when it was launched in March, but with a steady supply of extra doses, officials have been urging residents to re-book earlier when they are eligible.

Those who provided email addresses at the time of booking are being notified that way, but some of the mail apparently hasn't gone through.

Kevin Potter says his 90-year-old father and 88-year-old mother never received a notice.

"They never did get an email for some reason.  And I've checked their trash in their email system and it appears they were never sent," Potter told CTV News from his home in Bedford, adding his father tried to re-book over the phone, but couldn't get through.

As it stands, the couple's second shots are booked for July.

The provincial government today announced Nova Scotians who received their first dose of COVID-19 vaccine on or before May 1 and are scheduled to receive their second dose on or before Aug. 14 can reschedule their appointments for earlier dates.

As of Wednesday, 715,070 doses of COVID-19 vaccine had been administered, but only 58,854 Nova Scotians had received their second dose.

The CTV Vaccine Tracker finds that's just 6.8 per cent of the population.

"To see us basically last on second doses, it's pretty disheartening for Nova Scotians," said PC Leader Tim Houston.

"We went through the last few months we were last in first doses, and we only started to catch up because other provinces started to top-out."

But the province argues the rollout has been comparable with the rest of the country.

"Nova Scotia's vaccine rollout is in line with national averages," said Nova Scotia Health and Wellness spokesperson Marla MacInnis in a late afternoon email to CTV News.

"All provinces are in close proximity of each other in terms of achieving full vaccination.  As our second dose rollout ramps up, Nova Scotians are encouraged to book their second dose sooner."

"The vaccine booking site is a public resource where anyone can search for a clinic or appointment location near them. People who provided an email address at the time of booking will receive a rescheduling notice by email. In order to schedule a second dose appointment you will need to use the rescheduling link provided by email or you can call 1-833-797-7772 if you are currently eligible."

Many seniors seem to have been successful in doing that, according to the Canadian Association of Retired Persons.

"Now, for the most part, people seem to be getting through OK, although there's some wait," CARP chief policy officer Bill VanGorder told CTV News.

But he noted some seniors have noticed social media posts featuring much younger residents also getting their second shots.

"They don't mind, they're happy everybody's getting them, but they're wondering why the age, oldest to youngest plan, seems to have kind of fallen off the rails a bit," he said.

Kevin Potter agrees the booking system does appear to be working well – for most.

"But if you're an exception like my parents appear to be, there's no easy to break through the government 1-800 system and the computer system to get a booking."

The number for the Nova Scotia government toll-free booking line is 1-833-797-7772.