i have nothing but trouble with by over last few months and can’t get someone to take complaint serious.
is there a formal way to complain and is there an email address to complain to
If you are an existing BT account holder then the process is explained here.
There is no dedicated email address at the outset but it is often the way that, once submitted and processed initially, your case will be assigned to a named BT Customer Complaints agent - at that stage you would expect to have direct access (phone and email).
There is no email address you can use.
You can use the on line "contact us" or "Make a complaint" by using the Help button above
You then have to decide what the complaint is about
Follow it through and you will get to call or Online Chat which is Off Line so it looks like call or send them a letter.
To save you the journey, the number to call is 0800.800.150