Help or Advice please

Hoping one of you guys has some advice please. I currently have my office in a large garden building on my property. I have full fibre business into the garden building but only sky super fast in the house which is terrible. I've just been told I can never have fibre in the house as I already have the other line and extenders etc won't work. I wasn't told this when I took out the fibre line for the office. Is there anyway that this could be possible. I tried going with another provider for the house line but they nearly cancelled my business line in the process. Should add I'm not remotely technically minded so don't really understand what the problem is. Thanks in advance of your suggestions. I'm a small business and desperate for a solution.