personal guarantee hsbc

[yclept]

hi all
hope you can help 5 years ago i took out a loan with hsbc in my company name
25k i gave a personal guarantee for the loan at the time
this loan was paid in full ending April this year .

we have an overdraft of 20k

we also have a mortgage and an on demand loan
for a new building not yet completed
over the last few months they have slowly but surely pushed
up the intrest on the on demand loan to 5% above base and £268 per month renewal fee plus £350 a month admin fee
the forms were sent to me to sign
at this stage i ask why was the interest rate going up and up
and could they quantify the charges
to this i received a reply saying as i have not taken up there offer
please find alternative financing of the loan

we are now doing so
they also told us to find alternative banking and they were closing our account
from 5th dec
and they are calling in the overdraft against my personal guarantee

this brings me to the personal guarantee

i have two questions

have i been misled when taking out the original loan
(the loan was 25k the guarantee was for 25k)

but more important
i have a copy of the guarantee document
and believe it to be null and void
as it was incorrectly signed

i have signed it but i have also signed as the witness
underneath my signature as the witness
it says full name off witness (block letters)
this has been filled in with a bank officers name

i also believe the witness must be Independent
and not a bank employee

so the guarantee is unenforceable

any advise most appreciated

yclept