Blocked isn't settled.

A simple contract generally needs an offer, acceptance, something given in return, terms certain enough to enforce, and an intention to create legal relations. That last element matters most in family cases: arrangements between relatives are sometimes presumed to be domestic rather than legal, so evidence that repayment was genuinely expected — a stated date, a reference on the transfer, chasing messages — does real work. In practice these cases usually turn on evidence rather than paperwork.

Because a gift can't be reclaimed, borrowers often say the money was one. Courts look at all the circumstances — what was said at the time, what happened since. A reference on a transfer, an "I'll pay you back next month" message, or a first instalment are typically strong evidence of a loan, though the court weighs everything together. Where money passed on a basis that then failed entirely, the law of unjust enrichment can sometimes offer a separate route.

Where someone has been enriched at your expense and there's no legal basis for them to keep the money, the law of unjust enrichment can require them to pay it back — historically pleaded as an action for money had and received. It typically matters when a contract is hard to prove, when money was paid over on a basis that never materialised (the classic failure of basis), or where funds were transferred by mistake. In practice it is often run as an alternative alongside a contract claim rather than instead of one.

Where money is advanced for a particular purpose and that purpose fails — the deposit that never bought the car, the funds for a property share that never happened — the courts can in some circumstances treat it as held on trust for you rather than as a simple debt (the Quistclose line of cases). A constructive trust can also arise where someone holds property or funds it would be unconscionable for them to keep as their own. These routes are fact-sensitive and won't fit every loan, but they can matter where the recipient has little money left or the funds are traceable into something they bought.

Under s.5 the period for a simple contract claim is generally six years, normally running from the date repayment fell due rather than the date you lent the money. Sections 29–30 deal with fresh accrual: a part-payment, or an acknowledgement of the debt that is in writing and signed by the debtor, can start the six years again. Not every casual message will qualify, but a written admission can matter a great deal.

Where your agreement doesn't set its own rate, claimants can normally ask the court for statutory interest on the amount owed, calculated from when it fell due. On a long-unpaid loan this can add a meaningful sum, and it's set out in the claim rather than left for you to argue.

Part 6 governs service: a claim is normally served by post to the defendant's usual or last known residence, which is why blocking your number generally changes nothing. Part 12 covers judgment in default — where a properly served defendant files nothing within the time limits, the court can usually decide the claim without them.