From DSR:
Page 30
3.68 If goods develop a fault within the first six months of being sold,
the law presumes that the fault was there when you sold the goods –
unless you can show otherwise. You should not charge return costs
for goods that have been rejected because they are faulty.
a) you are quoting from the OFT Guide to Businesses on Distance Selling, not the DSR themselves.
b) if you look at the section you are quoting from, you'd see that this is informing businesses of other rights consumers may have beyond what they receive through DSR:
"After the deadline for cancellation has passed, a consumer
claims that goods are faulty or services do not conform to
the contract. Do I have to refund the consumer’s money?
3.67 In general the DSRs do not affect the consumer’s rights under other
legislation, for example the Sale of Goods Act 1979 or the Supply
of Goods and Services Act 1982. If the goods or services do not
conform to the contract and consumers exercise their rights to reject
them, you will have to refund their money.
3.68 If goods develop a fault within the first six months of being sold,
the law presumes that the fault was there when you sold the goods –
unless you can show otherwise. You should not charge return costs
for goods that have been rejected because they are faulty."
In general DSR specify the information an online/distance seller must provide about the purchase, and the right for a consumer to cancel for any reason within a given timeframe (with some type of good being excluded)
Sale of Goods cover the right to a refund, repair or replacement when the good doesn't conform to contract.
Matthew