Firstly I'm not an EA, although I do work with them, sorry if that's confusing you.
Secondly I'm not ignoring the fact that the EA was bad/negligent/failed to sell the property.
The costs of marketing a property are there whether the property sells or not. When a client agrees to market a property with an EA, the marketing costs should be set out for them and the client is liable for the marketing costs incurred on their behalf. They are normally agreed before the marketing campaign commences.
While the OP didn't sign the terms they received from the EA, it is likely (although bear in mind I'm going on limited information) that the marketing expenses were laid out in these terms or told to them in advance of the campaign. In any case, by allowing the EA to market the property - place signboards out front, advertise in press, place the property on myhome.ie/daft.ie - the client had some form of agreement with the EA, verbal or otherwise. Lets face it, if you don't want your property marketed, you're not going to allow anyone to put boards outside the house or stick it up on a website.
It is normal for an EA to charge the marketing expenses in the event that the property fails to sell or the client decides to change EA. This should also be set out in the terms the client receives.
To go back to the OP - the OP feels that they have justification that the EA didn't act properly on their behalf and did a bad job. They did remove their property from the EA books and the property is still on the market. If the OP feels that the marketing costs should not be paid by them, they should discuss this with the EA, express their dissatisfaction and explain why they do not want to pay the marketing costs.
You should be aware that many EA will bill for marketing expenses in the event that properties are taken off their books and/or do not sell. They may also bill for fees if a property sells through another estate agents in the period that they have sole agency rights or if the client sells privately when they have sole agency rights. Many EA will also chase a debtor who is not paying fees/expenses through solicitors and ultimately the courts if they feel it is warranted. I'm not saying that it's an acceptable manner to treat your clients, just that this is how it works for an EA.
In my opinion, marketing costs should be clearly set out in advance for the client and written acceptance of this should be obtained from the client before marketing of any property starts. I'm aware that many commercial EA companies in Ireland get marketing monies in advance and will not start a campaign without signed terms and marketing monies to avoid any confusion. Another way to tackle this would be to ask an EA to take on a "no foal, no fee" marketing campaign where the marketing costs are only payable in the event that a property sells. I'm aware of at least 3 EA who are now operating in this manner.