Barrie Marshall, who is promoting George Michael's final concerts in London next week, has called a ticketing problem which could threaten the events “sickening”.
Many ticketholders who purchased tickets for the concerts at Earls Court on Sunday and Monday used SOS Master Tickets, which has since become uncontactable.
Hundreds of fans began to voice their concern about the secondary market company when their tickets for last weekend's V Festival failed to arrive.
They were then told to collect their tickets from representatives of the company at the festival sites in Chelmsford and Staffordshire who never emerged.
As well as Michael's concerts, it's thought many people have used the company for this weekend's Reading and Leeds Festivals, and Madonna's forthcoming UK dates.
Speaking to the BBC, Marshall said: "It's very upsetting for us because we can't accommodate these people.
"So it's just really sickening, and there's very little we can do with it except try to have people deal with legitimate ticket agents."
The fiasco is likely to raise debate over the stability of the secondary ticket market, which earlier this year was subject to review by a select committee.
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