Landline repeatedly being called from same number

[DonsZ]

I called my home landline from my office number & now my home landline is being repeatedly called every few seconds from my office number.  I was still at work when the calls started and checked the office line which looks normal & does not appear to have a redial option or anything set. 
When you answer the home landline it just appears to be a dead line. 
Can anyone help with how I can stop this? 
Thanks