With faulty goods a seller is only obliged to provide a refund if you reject them within 30 days. (So the seller is, in part, correct).
However for six months after purchase he is still obliged to repair or replace such faulty items. (He can, of course, offer a refund instead but he's no longer obliged to).
Thereafter the seller remains obliged to repair or replace the goods if they fail due to an 'inherent fault' (i.e. something which was actually wrong with the goods at the time of purchase, such as the use of poor quality components or workmanship) but only if the purchaser can prove (e.g. by obtaining an independent report) that it was, indeed, an 'inherent fault' which caused the problem.
Any statement which tries to cut across your rights (such as "Nothing to do with me after 30 days, guv") contravenes the provisions of Schedule 2 of the Consumer Rights Act 2015 (as brought into effect under Section 62 of that Act) and is thus both unlawful and invalid.
As has been stated above, your contract is normally with the seller and not with the manufacturer. However under Section 30 of the Act you have an
additional contract with a guarantor (in this case the manufacturer), who is obliged to meet the terms of the guarantee offered by him.
http://www.legislation.gov.uk/ukpga/2015/15/contents/enacted