Marketing experts say Qantas is wasting its money on an advertising blitz to win back its passengers following the weekend's dramatic grounding, and that the airline should focus on its customer service and frequent flyers instead.

But they added the national carrier had built up enough "brand equity" to tide over its current crisis and survive challenges from its closest competitor, Virgin Australia.

Qantas promised a "special thank you" for its customers in full-page advertisements in newspapers today, saying: "Since the industrial action is over, no more aircraft can be grounded and no service cancelled ... You can now book Qantas flights with confidence and certainty.

"If you're one of our customers directly affected by the grounding, you can look forward to a special thank-you, to be announced soon."

The airline also sent a lengthy email to its 8 million frequent flyers last night, signed by chief executive Alan Joyce, which explained his decision to halt its flights over the weekend and strand about 70,000 customers worldwide.

A Qantas spokesman would not elaborate on what the planned "thank you" would be.

The Australian Competition and Consumer Commission demanded yesterday that the airline reimburse passengers for their losses -- such as hotel and transport costs -- following the grounding.

Public relations expert Tim Allerton told 702 ABC Sydney's Deborah Cameron this morning that Qantas's "advertising to date and for the next month or so is an absolute waste of time and money".

"Where I would be spending the money is on customer service, because one of the major complaints has been people have just not been able to communicate with anyone from Qantas, taking up to two to three hours waiting time to actually talk to a human being.

"And I just think that what they need to do is concentrate on that aspect to regain the trust, regain the rapport, especially with those frequent flyers."

Mr Allerton said Qantas had spent "hundreds if not billions of dollars over the past 90 years building up its brand" and the airline could draw on that to win back the loyalty of its customers.

"There's a huge amount of brand equity still in there that they can drawn on now they are having a time of crisis so I don't think we are anywhere near a tipping point in that there is so much brand equity in there," he told the ABC.

"What I think is going to happen next is that there is going to be a major price war and Qantas is going to try and get back some of that supposed loyalty by offering people very, very cheap fares."