Work advice! Need advice ASAP!

Ok, so I was randomly checking out my check stubs last night & I noticed a deduction for $21 that says “MISC- telephone”.. I went looking at more old ones & seen it on them too. So last year sometime, I got a company cell phone & it costs $21 out of every check to use it. Well, eventually I lost my work phone & being that it was for the company, they took the price of the phone out of my check last year sometime when I lost it. And now I notice they haven’t stopped taking $21 out of every check & it’s definitely been over 7 months for sure. I’d need the rest of my old check stubs to know how long exactly. The office is closed right now (it’s 6 am) but I do plan on contacting my supervisor as soon as they open at 8:30. My question(s) to you guys: Do you think they’ll realize their mistakes & reimburse me all of my money they’ve been unlawfully taking? Because I definitely want my hard earned coins back! And what am I to do if they try telling me they can’t or won’t reimburse my money? At this point, they owe me at LEAST $350. It could be more but I just added the 7 months I know for sure. Please give me some advice! Cause I’d hate to lawyer up on my job IF they be difficult & don’t correct the problem. They open in a few hours so some quick advice/responses would be splendid 😂

**UPDATE FOR THE ONES QUESTIONING MY MATH: Okay, so I clearly said they’ve been taking it out of EVERY check for as LITTLE as 7 months (meaning it’s most likely MORE than 7 months, I just have to get my stubs to count & check exactly how many).. and nowhere does it say I only get paid ONCE a month. Do y’all get paid only once a month? Cause you need a new job if so. And also, this job is very unorganized.. they have nee for years & this is NOT the first time or person they’ve made payment mistakes with. It’s a small company so they handle that themselves & as a business, it’s no way they should forget something like that on payroll for that long. Say what you want, sugar lumps but don’t insult my math & intelligence. I asked for advice, not a math lesson 🙃

And also, I would never go to my job trying to argue & go off on them because this is partly my fault as well. If I had been reading over my stubs correctly, I would’ve noticed it & had it fixed long ago. I just needed advice on what to do IF I had any complications because honestly.. the old me would’ve just been too timid to talk to them altogether 😂 And I kinda don’t know my rights or how to “defend” myself in the situation if it went sour & I don’t know if they’re actually obligated to reimburse the money.