A price-fixing cartel of estate agents in Somerset has been fined more than £370,000.
The firms colluded to set minimum commission rates for residential property sales at 1.5%, denying vendors the chance of a better deal.
Abbott and Frost, Gary Berryman Estate Agents, Greenslade Taylor Hunt and West Coast Property Services (UK) Ltd all admitted breaking competition law.
They were fined following a Competition and Markets Authority (CMA) probe.
'Best possible deal'
The firms were working in the Burnham-on-Sea area.
The CMA's Stephen Blake said: "Moving home is expensive and this shouldn't be made worse by estate agents conspiring to deny their customers the best possible deal, by agreeing not to compete on fees.
"Price-fixing cheats customers, and we are committed to tackling it regardless of the size of the businesses involved. We have taken action against estate agents before, and will do so again if firms break the law."
A spokesman for Garry Berryman Estate Agents said the company has "fully co-operated with the CMA in respect of its investigation relating to matters three years ago".
"The issues raised occurred entirely outside of company policy," he added.
Martin Crees of West Coast Properties said the company co-operated with the CMA "to a satisfactory resolution".
The BBC has contacted Abbott and Frost and Greenslade Taylor Hunt for comment.
The CMA said another company, Annagram Estate Agents Limited, which trades as C J Hole, will not be fined as it was the first company to confess its participation in the cartel.