What percentage of the price can I get refunded if the work is bad?

It depends on what's wrong, and on the defect category framework we use to keep recommendations consistent across disputes: Cosmetic only (paint splash, mess, scratches): 5–10% if not put right within the remediation window. Minor functional (a socket not working, a dripping tap): 10–25% if not put right. Major functional (job partly incomplete or significantly redone): 30–60%, with the tradesperson paid pro-rata for verified work. Complete failure (job not done, or needing to be entirely redone): 80–100%. Property damage is handled separately through the tradesperson's public liability insurance — see the property damage entry below.