Your question was asked from the offices of the grand maraji’ and this is their response:
The Grand Ayatullah Khamenei (may Allah prolong his life):
Retaliation from the creditor is only permissible when the debtor denies his debt or is negligent in paying it and there is no other way to reach your right except through retaliation. In other than such a case, taking his property will be without his consent and using it is impermissible.
The Grand Ayatullah Sistani (may Allah prolong his life):
If he owes you but refuses to fulfill it, although he admits to the debt, you can take whatever you can as retaliation.
The Grand Ayatullah Makarim Shirazi (may Allah prolong his life):
We don’t have information about this specific case, but generally speaking, if someone tramples another’s rights and that person has access to his property, he can take only enough to cover his debt, given that this doesn’t lead to any fasad (corruption/sin).
The Grand Ayatullah Safi Golpaygani (may Allah prolong his life):
In the mentioned case, it is better that you return to the store and peacefully get the rest of you pay from him, or to refer to just courts to solve the problem.
Ayatullah Mahdi Hadavi Tehrani (may Allah prolong his life):
If it isn't possible to solve the problem through friendly dialogue and lawful channels, you can take an amount equal to the debt from his belongings.