Hello - How are you today? I've been organizing to speak with you and I'm glad I got you...
Chit chat a little bit. Not a whole lot - you don't have a long message and the amount of time on the primary purpose of the call has got to be the majority of the call - at least 2/3. So keep it kinda short.

I know things have been slow. So we've been organizing a plan to get the business in a better direction.
Right away, or even some point later, the person you're speaking with may want to get into details. You've got to be firm and respond something like "I'll get into all the details when I deliver the plan, but let me organize with you right now - how we're going to get out of this challenge."

In about a week we'll have a successful plan to present to you how we can both succeed at this.
You have to pick the timeframe depending upon how hot the situation is. But in general the bigger the amount, the longer the relationship, you should easily be able to get a week to 10 days from this call. Why? It's entirely reasonable. Don't be dislodged from this point. Calmly.

I'll email you the plan so you can review and then we can meet either on the phone at an appointed time or in person. whatever you think is best.
Follow-up and on time delivery are quite key at this point. If you're on time and you did what you said you would do - you're promoting the right attitude.

I've get to get back to work - I looking forward to delivering a plan that will work for you and me. Have a great day - I'll speak with you next week.
There may be resistance to this view. Stay on message. It's the only one you got. You're making a new plan and it will dig everyone out of the hole - so long as everyone is cooperative. Stay on message and stay calm.