You need to use a product called Maxi Cleaner. This was developed especially for this type of problem. This is the strongest detergent cleaner that is available and if it cannot be removed with this then it will have to be recoloured. Always try the least option first.
Unfortunately when customers try things themselves they can leave the leather impossible to fix, especially if they have used products containing waxes or silicones as these sometimes make recoloring and refinishing very difficult.
Dye transfer is a common problem on light coloured suites. The use of a good Leather Protector (one that works) will help to inhibit this sort of problem and make it much easier to fix.
Give me a ring on 01423 881027 if you would like any further advice.
Regards
Judy