Hi all, can anyone offer me some advice please, I fitted a full head of u tip hair extensions yesterday, they looked lovely no problems, but today my client came back with lots of very large black marks on her extensions, I have no idea what this is, the extensions are from glamorous lengths and I had four packs in total of colours 18, 12, 22, I have photos if needed, I have emailed the company but no reply as yet what do I do??