my retention was 5% . my agent said most people just forget iit, by the way,that was in the days when you made a profit, not like today. so i never thought about it again…then about 1 year or more later i spotted a payment deposited into my bank account,
if you still want to make inquiries via your solicitors, get put through to the accounts department , after sales, they will have your details.also if you sold through an agent,call him ,
so based on my experience, it was dealt with in the next tax year.