Did you let the boot dry after using the RenoMat, and before applying the cream polish? If so, was the black mark gone once the area was dry? This will help determine if whatever was in the black mark is still a factor in the stain. I suspect what happened is that in your exuberance to remove the mark with RenoMat you applied too much, too hard. I love RenoMat, and think it is an essential in every shoe kit, but it is a very strong cleaner and should be used with care. Saphir does not list the cleaning agent used in the product, but from the smell I would say it is acetone or something similar. What probably happened is that the quantity of RenoMat you used opened the pores of the leather slightly and your rubbing opened them even more. Here is what I would suggest doing to salvage this boot (actually I would do both boots to keep them even): Go over the boots with a light coat of RenoMat to remove what wax you can. Rub gently, don't scrub. Let the boots dry. Then flush the oils, and other artifacts, out of the boots with water. To do this you need a soft sea sponge soaked in warm (almost hot, but comfortable to hold) water. Soak the entire boot (actually both boots to keep everything even) with the sponge. You can add some saddle soap to this process as well to help remove any lose induced pigment (leather dye is different). Do not scrub hard with the sponge, but rather blot and rub lightly. Let the boots dry overnight. The next day clean the boots with Renovateur (or other cleaner/conditioner). However, if the boots are still wet the next day (you probably got them too wet) let them dry another day before cleaning/conditioning. The water will tighten the leather pores back up to some degree, but it will also remove needed oils. This is why you want to use a cleaner/conditioner, or just a conditioner, after getting the boots wet to this degree. You can then polish the boots with the light brown cream polish once they have dried out from being cleaned/conditioned. If you do not have any cleaner/conditioner, then you can use the light brown cream only since it does have some conditioning oils in it. This may not be the perfect solution, but it should work to some degree. You can cover up any color deviation using a shade darker polish if need be, and chalk the whole thing up to experience.