Русско-англо-русский юридический словарь

Writing a formal letter of complaint remains an effective way to alert a company to a problem. [...] Before you begin your draft, gather all the information you will need to include in your complaint. This information may include the time, date, and location that you purchased faulty goods or services, reference or invoice numbers, and records of previous communication with the company. To support your complaint, you may need to enclose copies of documents such as receipts with your letter. (Oxford Living Dictionaries)

subsupplier. A supplier who provides goods or services to another supplier. Our supplier blamed its subsuppliers for the faulty components. (Wiktionary)

The most recent consignment of cloth was faulty. (Cambridge Dictionary)

If you notice a fault with something you’ve bought, you should report it to the retailer as soon as you become aware of it – delaying this could affect your rights. If you spot that something’s faulty within the first 30 days of owning the item, then you have the right to reject it and get a full refund, but you must tell the retailer within this period. [...] If you have a manufacturer’s guarantee or warranty, you may be able to make a claim against the manufacturer, but it’s usually best to raise issues with the retailer first. (The Telegraph)