Tenant Ignoring Late Fee Notices & Refusing to Pay

[Sean Peters]

Hello all,

I am currently in a situation where one of our retail property tenants is refusing to acknowledge and pay late fees as stated in the lease. This property is a family property and until recently it was managed by my elderly uncle.  As such, the tenants would regularly take advantage of his kindness and consistently pay late/ take actions that are not in accordance with the lease. 
 

The following is the issue and any/all suggestions will be greatly appreciated:

-Rent is due on the 1st of the month and there is a grace period until the 3rd.

-After the grace period has passed, in the lease it states that there will be a $25 late fee for the following 3 days and a $10 fee per day for each additional day. (When the lease was drawn up, I made sure that the late fee was reasonable as it is not for us to make additional money, just used as a tool to make sure that the rent is paid on time)

-The "Late Fee" section is listed under "RENT" in the lease.  That said, is this considered additional rent? (I ask as if it is, I assume I am able to serve a 3 day notice)

Additional Information

-Tenant is late in paying the rent on time 10 months out of the year

-I have sent out several notices to the tenant with tracking, to have proof that they received the letters.

-Tenant recently painted the exterior of the building without any consent from us.

Any suggestions on how I should proceed and what to do?  Thank you in advance.