[Estate agents’ address]
Ref: [address of seller’s property]
I have received your letter of [date] requesting payment in the sum of [£…] as the [….%] commission on the sale of the above property to [name of purchasers].
We instructed [other estate agent name] on [date], prior to our placing instructions with you, and it was on [date] that [purchasers] first inspected our property.
The fact that you subsequently issued particulars of our property to the purchasers is irrelevant, since it was [other agent] who introduced them to the property, which they eventually bought.
I therefore reject your claims to the commission.