British Airways has apologised after an “email error” meant some passengers were wrongly told their flights were cancelled following the announcement that pilots would strike for three days next month.

Weddings, honeymoons and holidays of a lifetime have been thrown into doubt by the walkouts, which will see a number of flights cancelled on 9, 10 and 27 September.

But it has now emerged that some passengers – the exact number has not yet been confirmed – were wrongly told that their flight would be cancelled and advised to rebook.

A spokesman for the airline said: “We are sorry that some customers received an email in error to say that their flight had been cancelled on non-strike days. We are getting in touch with all those customers this afternoon to clarify that their flight will go ahead as planned. We are sorry for any confusion and inconvenience this has caused.”

He said anyone who went on to spend money on alternative arrangements should contact British Airways “and we will deal with each case on an individual basis”.

The spokesman clarified that some flights on non-strike days would be affected, but that the bulk of those cancelled would be on the three strike days.

Numerous passengers on flights that will be grounded tried in vain to contact the airline to make alternative arrangements on Saturday. One told the PA news agency his 10-year wedding anniversary “trip of a lifetime” was in doubt after more than 100 calls to BA to get a refund went unanswered.

The airline’s customer service lines were jammed on Saturday morning after passengers booked on flights received emails overnight warning “a large number of delays and cancellations” were likely during the action.

The British Airline Pilots Association (Balpa) announced the strikes on Friday night after 93% of its members rejected an 11.5% pay rise across three years.

Scott Kishere, a filmmaker and police community officer, told PA: “My wife and I have been told that our flight to Toronto has been cancelled. This was a full package we booked through BA for our 10-year wedding anniversary. I have made over 100 attempts to contact them for a refund and they’re not answering.

“Until we get a refund, we do not have the money to rebook our trip of a lifetime. With the days counting down, it now looks unlikely we will be able to celebrate our 10-year anniversary as expected.”

Kishere, from Dorset, is one of hundreds of passengers who have tried desperately to contact BA via social media and its phone lines. He said he also planned to travel to Chicago for the city’s marathon with his partner a week after the final day of strikes, but feared that could also be impacted.

“We have worked so hard for these trips and BA do not have the decency or customer care to support us. For them this has been on the cards for a long time and I cannot believe they didn’t have a contingency in place.”

BA has said its proposed pay deal had been accepted by members of the Unite and GMB unions, which represent engineers, cabin crew and ground staff.

Balpa said more strike dates could yet be announced, adding that they were “a last resort and with enormous frustration at the way the business is now being run”.

The airline said it would offer refunds and rebookings, adding: “We will do everything we can to get as many people away on their journeys as possible.”