Ms Bonafede's number was switched to a new handset and her address and bank details were accessed.
She said the company failed to take the data breach seriously and she had to involve police.
EE "sincerely apologised" to Ms Bonafede, and said the employee no longer worked for the company.
'They didn't seem concerned'
After five days with no signal, she was told someone had visited an EE shop, requested a new Sim card and switched the account to a new handset.
When the call centre handler read out the new address registered on the system, she recognised it as that of her ex-partner - who worked at one of the firm's High Street stores.
It could have meant all texts and calls made to her during that period would have gone to him.
"The only way he could have known about my new address was through the data breach"
Despite being given assurances that EE would investigate, she said it was not until she started publically tweeting about the problem that the company started taking it seriously.
"He had access to everything: my sort code, my account number, a photocopy of my driver's licence.
"It did put me at risk and I feel all customers should know how poorly something like this will be handled if there is a data breach on their account.
"It was a complete breach of trust. I don't trust the way they handled my data at all."