Not paying

[tentmadam]

To cut a very long story short my mum died(intestate)) her home was left to my siser and I . She would't sell out to me but she wouldn't pay bills, maintain property.She has now died her children have had home valued at way over actual value by not declaring a few aspects at the house i.e. sitting tenant on the land.Parents buried at the house!Their dad (who my sister had divorced) offered to be an unbiased go between which I was happy with.Turns out he is a very biased go between! He has now told us they have had enough, want to buy us out and will not settle bills until we decide to sell.We had the place looked at by a surveyor because the house has been in the family since the 50's and have offered them half the value but they want £60,000 more!Their plans are to do up and sell. Ours is to keep it in the family and retire there.We delivered a letter to their solicitors(they have kept on the one who did their mum's probate ) we are not using one as we thought they were family! giving them 28 days or we will take court action but don't know if this best /legal way.Any ideas gratefully received.Thank you