I am sorry to hear about your bad shopping experience. I am writing this email to give you some advice regarding your case on the individual items.
The amended Sale of Goods Act 1979 requires the seller to supply goods of satisfactory quality. This includes that the goods must be durable and fit for their general purpose. Therefore you are able to take the jeans and shoes back either for a full refund or a replacement.
The Dior perfume company has breached the law of negligence because a duty of care was not carried out. Also this breach was the direct cause of damage which was the rash came out after using the perfume. Therefore under the Consumer Protection Act 1987, your mother has the right to sue the manufacturer.