Your family size does not usually change your consumer rights: the retailer is responsible for goods that are not of satisfactory quality, fit for purpose or as described. Under the Consumer Rights Act 2015, you can normally reject faulty goods for a refund within 30 days, although later remedies may involve a repair or replacement before a refund or price reduction is available. Contact the retailer, explain the fault and keep your receipt, photos and any relevant costs. Check the guidance on GOV.UK or Citizens Advice if the retailer disputes your rights.