Agents face the prospect making last minute flight changes for clients in the August peak as British Airways cabin crew prepare to take further strike action.

The Unite union has warned BA that it has until Tuesday (June 29) to find a solution to the dispute or it will ballot its members for a further strike.

The union, which represents almost 12,000 cabin crew at the airline, highlighted three issues which need to be resolved.

Cabin crew have already staged 22 days of strike action which has cost the airline an estimated £154 million this year alone.

If BA fails to reach a solution, the ballot will open on Tuesday and close on July 27 – meaning that the next walk-out could start in the first week of August.

Unite identified the main issues under dispute as being BA’s use of other staff to work as cabin crew; the removal of travel perks from crew who have been on strike and “vindictive, disproportionate and unnecessary” disciplinary action against some of its members.

Unite officer for civil aviation Brian Boyd said: “Unite has consistently tried to find a negotiated settlement to the original items of dispute.

Unfortunately there has been an unwillingness from the company to take a step back from its position of confrontation.

“These three new items have been caused by the BA’s vindictive behaviour towards employees who participated in lawful industrial action and the ongoing disregard the airline is displaying towards its own workplace agreements.

“Once again, we say to BA. Do not seek conflict. Drop the tough talk and work with us to deliver the change needed for the future and preserve the standards associated with this great airline.”

But BA appeared to be sticking to its hard line stance, with a spokesman saying that the union’s “apparent wish to target the summer holidays of tens of thousands of families is deplorable.”

The airline claims to have strengthened contingency plans in place and aims to fly all of its Heathrow long haul programme and a “substantial proportion” of short haul routes.

Flights from Gatwick and London City Airport will be unaffected, BA pledged.