You had an agreed repayment structure with the council and they have reneged on it and you are on a low income. You have grounds to file a complaint of misfeasance against the council with the
LGO, so get that on its way ASAP given the urgency of the matter. Ask the council why they have send bailiffs, if its an error then you can ask the LGO for compensation because the council made a mistake.
NEVER open the door to a bailiff and ALWAYS speak to a bailiff through a window or letterbox. If you can, throw them a letter based on
(EDIT) to tell them they are not being given access to your goods and property. It revokes a walking possessions fee and an attending to remove fee. If you want to post the letter to the bailiff then use
(EDIT) instead and cc a copy to the council.
If you ever feel threatened, intimidated or a bailiff threatens you with a locksmith then you should call police on 999 reporting a robbery in progress with a suspect on the premises.
Bailiffs can only be sent if the council has a liability order - did you receive one? its a Form B.
The bailiff tried to trick you into signing a walking possessions agreement telling you it was something else - such as confirmation of visit - you did the right thing by not signing but this now gives you grounds to make an official complaint against the bailiff for attempting to defraud you because that signature would have enabled the bailiff to charge to a walking possessions fee.
If you know the bailiffs name, then
(EDIT) and report back of you find an irregularity.